It seems you don't want to enforce the no contact/transparency plan, so you will have these feelings you are having for a long time.
AND, if he IS seeing her, all of this time you are spending "making this work" will be for nothing. AND I would even say you may be losing out on an opportunity to save it by NOT enforcing this. By not doing so, you could be looking weak/enabling/pathetic in his eyes, and the OW will not look like this. It will also be hard for him to stop the addiction and he may not be able to without your help. Seeing a counselor could help, but if he is still seeing her it will not.
